We implemented a multivariate approach to investigating the effects of SNPs in dopamine genes, a theoretically implicated neurobiological system, on sensation seeking, a personality trait associated with costly outcomes, such as substance use disorders. Working with data from 635 individuals, we selected 273 SNPs covering eight dopamine genes, and conducted initial association analyses to identify individual SNPs significantly associated (at p<0.05, FDR < 0.10) with sensation seeking. We then estimated the variance in sensation seeking explained by 1) demographic covariates; and 2) all significantly associated SNPs. Increased variance explained and improved model fit statistics (see Table 3) indicated that aggregated SNPs from dopamine genes explained significant variation between individuals in sensation seeking, even when controlling for demographic characteristics. Despite our relatively dense coverage of these selected genes, not all possible SNPs (or other genetic variants) were included on our genotyping platform. To the extent that the genotyped SNPs are not themselves functional, but are instead in linkage disequilibrium (i.e. correlated) with ungenotyped functional variants, these proportions of variance may be underestimates compared to the true variance in sensation seeking explainable by these dopamine genes.
